Acoustic diaphragm



July 2, 1929. ND 1,719.472

ACOUSTIC DIAPHRAGM Filed June 12, 1926 Patented July 2, 1929.

UNITED STATES PATENT OFFICE.

NEWMAN H. HOLLANQ'OF MONTCLAIR, NEW .TERsEY, ASSIGNOR 'ro BELL TELEPHONELABORATORIES, INCORPORATED, OF NEW YoEx, N.- Y., A CORPORATION OF NEWYORK. t

ACOUSTIC IJIAPIBIR AGIMI.

Application filed June 12, 1926. Serial No. 115,476.

by winding a light tubular material in the form of a flat spiral, theadjacent convolutions of which are held in contact by an ad-' hesivesubstance.

A preferred form of the invention is shown on. the attached drawing inwhich Fig. 1 is a frontfiiew and Fig. 2 a view in partial section of thediaphragm mounted in a phonograph sound box. 7

As illustrated, one'end of apiece of light tubular material, such asstraw, is attached. to a small spool-shaped piece 4, which may be ofmetal, and is then wound in the form of a -fiat spiral substantially asshown. The spirals may be made by any of the well known methods ofcoiling or bending tubular materials. When tubular straw is used it maybe coiled by the method employed in making straw hats of similarmaterial. Tubular straw has the. advantage of lightness over metal tubesalthough itis more difficult to wind owing to the tendency of the strawto kink or collapse at intervals especially when the radius of the bendis small. However any kinks that occur do not noticeably affect theoperation of the diaphragm. During the winding process a small amount ofadhesive material, such for example as a moisture proof element, isintroduoed so that adjacent eonvolutions are held together. The outsideend of the tubular material may be tapered as shown at 5 either bycutting the end of the tube on the bias or collapsing it.

\Vhen appliedto a phonograph sound box the diaphragm is clamped betweenrings 6 of a resilient material such as rubber by a cap 7 which isattached to the main body 8 of the sound. box by means of a number ofscrews 9. The pressure of the rings 6 on the diaphragm should only besuflicient to insure an air-tight joint.

The stylus arm 10, attached to spool 4 and pivotally supported at 11,has a needle 12 held therein which cooperates with a phonograph record,not shown. The vibrations of the record are transmitted to the diaphragmthrough the needle and stylus arm.

\Vhat is claimed is:

1. An acoustic diaphragm light. tubular material woun in a spiral. r a

2. An acousticv diaphragm comprising a plurality of convolutions of alight tubular material. I

'3. An acoustic diaphragm comprising a plurality of convolutions of atubular material, the adjacent convolutions being in contact. I

4. An acoustic diaphragm comprising a plurality of convolutions'ofstraw.

5. An acoustic diaphragm comprising a plurality of convolutions'ofstraw, adjacent convolutions being held in contact by an adhesivesubstance. Y

In witness whereof, I hereunto subscribe my name this 10th day of JuneA. D., 1926.

NEWMAN H. HOLLAND.

comprising the form of

